scd: Add special serialno compare for OpenPGP cards.

* scd/app.c (is_same_serialno): New.
(check_application_conflict): Use this.
(select_application): Ditto.
(app_switch_current_card): Ditto.
* scd/app-openpgp.c (check_keyidstr): Ignore the card version and also
compare case insensitive.
--

This is required because we change what we emit as serialno of OpenPGP
cards but existing keys still use the old form of the serial
number (i.e. with a firmware version).

See-commit: 3a8250c020
Signed-off-by: Werner Koch <wk@gnupg.org>

doc/HACKING

@@ -220,6 +220,7 @@ Note that such a comment will be removed if the git commit option
   - Regression-due-to :: Commit id of the regression fixed by this commit.
   - Fixes-commit :: Commit id this commit fixes.
   - Updates-commit :: Commit id this commit updates.
+  - See-commit :: Commit id of a related commit.
   - Reported-by :: Value is a name or mail address of a bug reporte.
   - Suggested-by :: Value is a name or mail address of someone how
                     suggested this change.

scd/app-openpgp.c

@@ -1102,8 +1102,8 @@ do_getattr (app_t app, ctrl_t ctrl, const char *name)
 
   if (table[idx].special == -1)
     {
-      /* The serial number is very special.  We can't use the the AID
+      /* The serial number is very special.  We can't use the AID
-         DO (0x4f) becuase this is the serialno per specs with the
+         DO (0x4f) because this is the serialno per specs with the
          correct appversion.  We might however use a serialno with the
          version set to 0.0 and that is what we need to return.  */
       char *serial = app_get_serialno (app);
@@ -5031,7 +5031,10 @@ check_keyidstr (app_t app, const char *keyidstr, int keyno, int *r_use_auth)
             return gpg_error (GPG_ERR_INV_ID);
         }
 
-      if (n != 32 || strncmp (keyidstr, "D27600012401", 12))
+      /* For a description of the serialno compare function see
+       * is_same_serialno.  We don't use that function because here we
+       * are working on a hex string.  */
+      if (n != 32 || ascii_strncasecmp (keyidstr, "D27600012401", 12))
         return gpg_error (GPG_ERR_INV_ID);
       else if (!*s)
         ; /* no fingerprint given: we allow this for now. */
@@ -5039,7 +5042,9 @@ check_keyidstr (app_t app, const char *keyidstr, int keyno, int *r_use_auth)
         fpr = s + 1;
 
       serial = app_get_serialno (app);
-      if (strncmp (serial, keyidstr, 32))
+      if (!serial || strlen (serial) != 32
+          || ascii_memcasecmp (serial, "D27600012401", 12)
+          || ascii_memcasecmp (serial+16, keyidstr+16, 16))
         {
           xfree (serial);
           return gpg_error (GPG_ERR_WRONG_CARD);

scd/app.c

@@ -155,6 +155,35 @@ apptype_from_keyref (const char *keyref)
 }
 
 
+/* Return true if both serilanumbers are the same.  This function
+ * takes care of some peculiarities.  */
+static int
+is_same_serialno (const unsigned char *sna, size_t snalen,
+                  const unsigned char *snb, size_t snblen)
+{
+  if ((!sna && !snb) || (!snalen && !snblen))
+    return 1;
+  if (!sna || !snb)
+    return 0;  /* One of them is NULL.  (Both NULL tested above).  */
+
+  if (snalen != snblen)
+    return 0;  /* (No special cases for this below).  */
+
+  /* The special case for OpenPGP cards where we ignore the version
+   * bytes (vvvv).  Example: D276000124010304000500009D8A0000
+   *                         ^^^^^^^^^^^^vvvvmmmmssssssssrrrr  */
+  if (snalen == 16 && !memcmp (sna, "\xD2\x76\x00\x01\x24\x01", 6))
+    {
+      if (memcmp (snb, "\xD2\x76\x00\x01\x24\x01", 6))
+        return 0;  /* No */
+      return !memcmp (sna + 8, snb + 8, 8);
+    }
+
+  return !memcmp (sna, snb, snalen);
+}
+
+
+
 /* Initialization function to change the default app_priority_list.
  * LIST is a list of comma or space separated strings with application
  * names.  Unknown names will only result in warning message.
@@ -357,8 +386,8 @@ check_application_conflict (card_t card, const char *name,
 
   if (serialno_bin && card->serialno)
     {
-      if (serialno_bin_len != card->serialnolen
+      if (!is_same_serialno (card->serialno,  card->serialnolen,
-          || memcmp (serialno_bin, card->serialno, card->serialnolen))
+                             serialno_bin, serialno_bin_len))
         return 0; /* The card does not match the requested S/N.  */
     }
 
@@ -734,8 +763,8 @@ select_application (ctrl_t ctrl, const char *name, card_t *r_card,
       lock_card (card, ctrl);
       if (serialno_bin == NULL)
         break;
-      if (card->serialnolen == serialno_bin_len
+      if (is_same_serialno (card->serialno, card->serialnolen,
-          && !memcmp (card->serialno, serialno_bin, card->serialnolen))
+                            serialno_bin, serialno_bin_len))
         break;
       unlock_card (card);
       card_prev = card;
@@ -805,8 +834,8 @@ app_switch_current_card (ctrl_t ctrl,
     {
       for (card = card_top; card; card = card->next)
         {
-          if (card->serialnolen == serialnolen
+          if (is_same_serialno (card->serialno, card->serialnolen,
-              && !memcmp (card->serialno, serialno, card->serialnolen))
+                                serialno, serialnolen))
             break;
         }
       if (!card)